This invention relates to an optical indicator device.
Optical indicator devices have already been used biologically for the measurement of concentrations of specific particles. In these devices the indicator was provided with a membrane which was permeable in a selective manner by specific particles through diffusion and means were provided at the opposite side of the membrane to cause the optical indication of the concentration of particles which had penetrated the membrane. Through the separation of the specific particles entering the inner indicator space from the known amount of other particles, a fairly exact measurement could be accomplished.
This type of measurement and indicating device is free of undesirable reaction on the test subject and furthermore is not likely to result in wrong measurements. The device, besides, is quite sturdy and can be used without special preparation. This type of indicator has, however, heretofore been used only for measuring concentrations. Indicators for measuring other physical parameters have not been available. However, in biological practice which has to do with living tissue the measurement of pressure or temperature is extremely important if a reaction on the test subject through undesirable degrees of concentration is to be excluded.
For instance, the control of the temperature parallel with the measurement of the glucose concentration is of great significance since there occur temperature variations up to 10% which, for instance in case of diabetics. are not tolerable.
It is therefore an object of the present invention to provide for indicators which are optically responsible to physical parameters. An incidental object is that such indicators must be available without undue expense and must be usable without complex preparations.